egg drop (pair teams, two adults with one child) carrier bag of bits each, paper, loo rolls, selotape string etc and a raw egg each, 10 mins to build something to drop egg out of bathroom window without it breaking.
chubby bunny (taking one marshmellow at a time pop in mouth and say chubby bunny, winner is person with most in mouth still able to say chubby bunny - provide bowles to spit out at the end)
Name the christmas tune - one person on Utube music, others in teams short burst of songs for everyone to guess.
mini-snowmen - cheap tubs of icecream, value sultanas, ribbons and scrapes of paper, in pairs build a snowman on a plate.
Twister. If you haven't got a mat, do 2 person twister, where person A has to put body part X to person B's body part Y. Write lots out on little bits of paper, fold them up and put them in a handy receptacle. Call them out and have a camera handy!
Otherwise, hide and seek? Musical statues/chairs/bumps/cushions? Limbo?
they may be a bit small it is the game where first person chooses a gift from a selection (eg you could wrap up your prizes, really fun if you wrap up a couple of boobie prizes for older children). The next person then has a choice to steal that present or open a new one. If they steal the victim gets to choose a new one. It pays to be the last to go as you can see all but one present and decide whether to steal or open. At the end you can do all sorts of variations such as anyone who hasn't stolen anything has a chance to steal or the one who has had the most things stolen off them has a chance to steal.
With your ages I would maybe do a treasure hunt for the kids or find the adult (most adults hide and perhaps some could hide with a prize) kids are helped to find them and keep the prize.